Charging System Troubleshooting--Blown Ignition Light Fuse?

[ACHiPo]

Originally Posted by patrickt

That's progress. For the next set of tests, you will leave the double green wire disconnectied from the light for everything below.

1) Remove the G/R wire from the ignition light but leave your fused jumper wire running to the light. Turn the ignition switch ON but do not start the car. Touch a known good ground lead to the exposed pin of the light and observe that it illuminates. Then, using a VOM, test for either a) 12v+, b) 12v-, or c) neither one at all at the disconnected G/R wire. Report the findings.

2) Plug the G/R wire back on to the ignition light. With the ignition ON, and the car not running, the light should be "ON" but you report that it is not. Try running a known good ground wire to the alternator and voltage regulator and touch different spots on both those components just to see if you can get the ignition light to illuminate. For instance, touching a known good ground wire to the VR case and making the light come on each time you did that would be a really nice sign. Report back.

3) Insert a fuse in to Fuse #3 and turn the key ON, but do not start the car. See if your gauges, heater, and wipers work or if you blow the fuse doing that. Report back.

We are making progress.

First test did not show any voltage or illumination. I ran a ground wire from the engine block to the center pin of the ignition bulb with the ignition "ON" and no illumination. Checked with a DVM and sure enough no voltage across the connections.

Running second test now...